1 . Field of the Invention
The present invention relates to a printed wiring board including a core substrate and buildup layers formed on upper and lower surfaces of the core substrate, and a method of manufacturing the same.
2 . Description of Background Art
In a printed wiring board described in JP 2008-85106 A, a core substrate constructed by laminating three resin layers formed by impregnating resin into fibers arranged in one direction is used. The number of fibers per length of resin layer positioned in the center of the resin layers is set to be greater than the number of fibers per length of other resin layers. Therefore, the thermal expansion coefficient in a planar direction becomes uniform over the entire core substrate, and warpage of the printed wiring board and undulation of the surface of the printed wiring board are suppressed. The entire contents of this publication are incorporated herein by reference.